U.S. Pat. No. 5,935,039 and Tokkai Hei 10-220551 published by the Japanese Patent Office in 1998 disclose an infinite speed ratio transmission device for a vehicle wherein a fixed speed ratio transmission and a planetary gear set are combined with a toroidal continuously variable transmission (CVT) in order to increase the speed ratio range of the CVT. In this device, an engine output is input into the CVT and the fixed speed ratio transmission.
The output shaft of the CVT is combined with a sun gear of the planetary gear set, and the output shaft of the fixed speed ratio transmission is combined with a planet carrier of the planetary gear set via a power circulation clutch.
A ring gear of the planetary gear set is joined to a final output shaft of the transmission device which drives the wheels. The output shaft of CVT is also joined to the final output shaft of the transmission via a direct clutch.